Digital Imaging and Other Ancillary Tools for Hair Transplantation Evaluation

18 Digital Imaging and Other Ancillary Tools for Hair Transplantation Evaluation

Alessandra Juliano

Summary

In evaluating a person for a hair transplant, it is very important to take specific measurements of follicular unit density in the donor area. There are different tools to document and quantify hair density and plan the procedure such as the following: hair densitometer, videomicroscopy, Folliscope, Follysis, HairCheck, FotoFinder with TrichoScan and TrichoScale, and the ARTAS Hair Studio. Using technological advancements in digital imaging for hair loss can help in determining appropriate candidacy for hair restoration surgery and also guide the surgeon to achieve more consistent results.

Keywords: hair density hair miniaturization trichogram photo documentation patient consultation hair transplant tools

Key Points

•There are several tools to evaluate donor density which can determine patient candidacy as well as aid the surgeon in achieving more consistent results.

•The densitometer can be used to assess donor density, follicular unit composition, and the presence of miniaturization in the donor area.

•With more recent technology and advances in digital imaging, quantitative measurements of the donor area can be performed with immediate results and patient archiving features.

18.1 Introduction

In evaluating a patient with androgenetic alopecia for a hair transplant, typically the physician determines the patient’s Norwood Class, designs the recipient area on the scalp, “eyeballs” the number of grafts needed as well as the number of grafts that can be obtained from the donor area, and then decides upon the appropriate number of grafts for the session. In many cases, taking specific measurements of donor follicular unit density and assessing donor area quality with respect to composition of terminal versus miniaturizing hairs are not performed. These parameters, however, are important variables in deciding which patients are good candidates for hair transplantation and in determining the size of the donor area needed to obtain the number of grafts that are necessary for the procedure.1

18.2 Background

One of the earliest methods of measuring hair density was devised by Bouhanna, who used camera attachments to create a “phototrichogram,” an ultra–close-up photograph of hair exiting the scalp. This method provided the capability to document the quality and quantity of hair shafts. However, the disadvantage of this innovation was that an assessment could not be done until after the film had been developed.²

A number of other handheld instruments to measure density have been developed with the similar basic elements of magnification, illumination, and a calibrated field or ruler. With more recent technology, digital trichograms allow the physician to take quantitative measurements of hair shaft diameters and provide an immediate, permanent record of this information.³^,⁴^,⁵^,⁶

The use of technological advancements in digital imaging with global evaluation systems of hair loss patterns and characteristics can help in determining appropriate candidacy for hair restoration surgery. This can optimize the chances of achieving more consistently pleasing cosmetic results by identifying poor or borderline candidates.

18.3 Densitometry and Videomicroscopy

In 1993, Rassman and Bernstein introduced the hair densitometer, which is a small ×30 magnification instrument to help physicians measure density and detect miniaturized hair. Densitometry is a technique that analyzes the scalp under magnification to give information on hair density, follicular unit composition, and degree of miniaturization. It can be used to help evaluate a patient’s candidacy for hair transplantation and help predict future hair loss in areas affected by AGA.⁷

The hair densitometer is a self-contained, portable, device that houses a magnifying lens and an opening of predetermined size (Fig. 18.1). The hair is clipped short (~ 1 mm) and the unit is placed directly on the scalp. An assessment is made from a standard 10-mm² field. Multiple measurements taken from different parts of the scalp are often helpful, particularly if there is significant variability from one location to another.¹

Fig. 18.1 The Rassman hair densitometer. Quick look at follicular density.

An advantage of the handheld densitometer is that it is inexpensive and readily available to be used during the consultation and can provide immediate information regarding a patient’s candidacy for surgery.

The densitometer was initially used to quantify a patient’s donor density, estimate the total number of grafts that could be safely obtained from the donor area, and help predict the decrease in donor reserves over subsequent transplant sessions. With the introduction of follicular unit transplantation in 1995, densitometry began to be used to assess follicular unit composition (the number of terminal and miniaturized hairs that each individual unit contained) and follicular unit density (the spacing between units). These additional factors were found to be important in the assessment of the donor supply and in the overall surgical planning of follicular unit transplantation procedures.⁸^,⁹^,¹⁰

The use of densitometry was soon expanded to guide the surgical treatment of those with racially distinct hair characteristics, to improve the diagnosis and treatment of balding women, and to further define the conditions of diffuse patterned and unpatterned hair loss.¹⁰^,¹¹^,¹²

18.4 Densitometry Measurements

When determining a patient’s candidacy for hair transplantation, densitometry can be used to measure the donor hair density (i.e., number of hair/mm²), the composition of follicular units (i.e., the number of 1-, 2-, 3-, and 4-hair units), and the degree of miniaturization.

Although the precise hair density and composition of follicular units will not be known until after the donor strip has been completely dissected, densitometry can be used to approximate hair density at the time of the consultation. This will enable the doctor to predict how much hair will be obtained from a certain size strip or the number of grafts that can be extracted via follicular unit excision (FUE) within a defined donor area.

18.5 Folliscope

Folliscope (2006) is a digital imaging device, which enables the development of a phototrichogram. Folliscope is a simple USB connection–based device that is connected to a computer and screen (Fig. 18.2). The small handheld apparatus contains a high-definition microscopic camera that is capable of taking images from ×1 to ×300 magnifications, at 2,048 × 1,536 pixel resolution within an area up to 1.7 cm². It has the advantages of clearly visualizing the hair and assisting the physician to measure hair density and hair shaft diameter as well as the proportions of different hair types: terminal and vellus hairs. To do the measurements, the physician must first tag the individual hairs before the software calculates the hair density and hair diameters.⁷

Fig. 18.2 Overview of the Folliscope software. Uses digital imaging to measure and calculate follicular and hair density. Some models can measure caliber and other parameters.

The values of different trichological parameters can also be compared with previous measurements for the same patient, providing valuable assessments of disease course and response to therapy. There is no need to have the hair plucked or clipped, it is performed on a dry scalp, and adding an immersion fluid or a hair dye is not usually needed.

The use of Folliscope to compare the differences between the donor and the recipient area can also provide objective and predictive evidence regarding the question: “How good a surgical candidate is the patient?” The donor density can be measured in multiple areas providing an estimate of donor supply. A decreased density or a greater percentage of miniaturized hair in the donor area would caution against performing a hair restoration procedure, while a patient with higher density and very few miniaturized hair would be a better candidate. Visualizing increased miniaturization in the recipient area may indicate the presence of hairs at risk of shock loss as well as greater likelihood of progression of AGA and an expanding recipient area. The Folliscope is also useful as an educational tool during the consult. The ability to show the patients their donor and recipient characteristics in real time on the computer screen during a consult is an aide in setting realistic expectations.

18.6 Follysis

The Follysis system was developed in 2014 by a group of medical physicists at the University of Patras in Greece. The system includes database image analysis techniques, provides hair transplantation treatment planning, and patient follow-up tools (Fig. 18.3). It combines mathematical formulations, database analysis, and graphical interpretation.

Fig. 18.3 Follysis image analysis calculating multiple parameters such as number of FUs/cm² and hair/FUs ratio. Distance between FU and hair caliber.

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